Unban an IP properly with Fail2Ban
1. find the right jail to unban:
fail2ban-client status | grep "Jail list" | sed -E 's/^[^:]+:[ \t]+//' | sed 's/,//g'
to get the actual jail names.
2. use this to find the iptables rule name:
iptables -L -n
The rule name and jail name may not be the same but it should be clear which one is related to which.
Normally in iptables output you can find 'f2b-<jail_name>' naming: consider only 'jail_name' (i.e. omitting 'f2b-')
3a. with Fail2Ban
v0.8.8 and later:
fail2ban-client set <jail_name> unbanip <ip_address>
Where <jail_name> is the jail name, and <ip_address> is the IP address to unban.
3b. With Fail2Ban
before v0.8.8, the syntax is different:
fail2ban-client get <jail_name> actionunban <ip_address>